Radio alarm system

摘要

Electrically conductive leads of a radio alarm system electrically connect a relay, a source of electrical energy and a radio transmitter in a back up circuit. The relay is energized by electrical conductors of an electric circuit of the radio alarm system having switches, and maintains the relay normally open as long as the radio alarm system is in operative condition. When an electrical conductor of the radio alarm system is open-circuited, the relay is deenergized and closes the back up circuit to actuate the transmitter to transmit radio signals indicating that an electrical conductor of a closed circuit of the radio alarm system has been open-circuited.